Let’s talk about sex. No, not that sex, but the word “sex” and how the U.S. Supreme Court will interpret it in one of the nation’s most important anti-discrimination laws.

The law in question is Title VII of the Civil Rights Act of 1964, which you probably know as the crowning achievement of the civil rights movement. The act banned segregation on the grounds of race, color, religion and national origin, in all places of public accommodation. And Title VII specifically focused on the workplace and employers. It prohibits employers from discriminating against workers because of their race, color, religion, national origin or sex. Title VII also created the Equal Employment Opportunity Commission (EEOC) to bring lawsuits on behalf of workers who claim discrimination.

The part of Title VII that bars employers from discriminating “because of…sex” is at the heart of three cases that the Supreme Court will hear Oct. 8, during the first week of the new 2019 term.

The three cases have triggered a tsunami of amicus briefs with opinions from across the political, ideological and other spectrums.

For oral arguments, the justices have combined two of the cases because they both ask whether sexual orientation is included in the ban on discrimination because of sex. The third case, which will be argued separately, asks if the same ban prohibits discrimination against transgender persons, as well as sex stereotyping, which the Supreme Court has already said violates Title VII, in a 1989 ruling known as Price Waterhouse v. Hopkins.

Not surprisingly, the three cases have triggered a tsunami of amicus briefs with opinions from across the political, ideological, religious, academic, health, labor and business spectrums. The briefs in the transgender case can be found here and the briefs in the two sexual orientation cases can be found here. And you can read transcripts of the Oct. 8 arguments later that day and listen to the audio on Oct. 11 on the court’s website.

Here’s a look at who’s involved and what arguments are being made, starting with the two combined cases.

Does Title VII cover sexual orientation?

Don Zarda was a skydiving instructor at Altitude Express in Long Island, New York. He occasionally took clients on tandem jumps. He often revealed to female clients that he was gay in order to make them feel more comfortable when strapped to him for the jump. But after one tandem jump, a female client, to whom he had told his sexual orientation, claimed he touched her inappropriately. Although Zarda denied the claim, he was fired in 2010. Altitude Express contends Zarda was fired because he had a history of similar complaints of inappropriate behavior. Zarda’s suit claimed he was fired because he “honestly referred to [his] sexual orientation and did not conform to the straight male macho stereotype.” Zarda died in 2014 in a base jumping accident. His family has carried on his discrimination case.

Gerald Bostock was a public employee for more than a decade as the Child Welfare Services coordinator for the Clayton County Juvenile Court System in Georgia. He claims he was falsely accused of mismanaging funds as a pretext for firing him after the county learned he was gay. He filed a complaint with Equal Employment Opportunity Commission (EEOC), which, in turn, sued the county for sex discrimination.

Why they went to the Supreme Court: A federal appellate court ruled in Zarda’s favor, finding that sexual orientation discrimination is included in a subset of prohibited actions taken on the basis of sex. But in Bostock’s case, a different federal appellate court disagreed, relying on a prior decision that being fired “for homosexuality is not prohibited by Title VII.”

As mentioned earlier, both are seeking the answer to the question: Is sexual orientation included in the ban on discrimination because of sex?

Bills to add sexual orientation to Title VII, writes the U.S. solicitor general, have been introduced in every Congress since 1975.

The EEOC in 2015 took the position that “sexual orientation is inherently a ‘sex-based consideration,’” and that allegations of discrimination based on sexual orientation qualify as allegations of sex discrimination under Title VII. The EEOC also declared that sexual orientation discrimination is sex discrimination because it involves discrimination based on gender stereotypes.

Since then, the EEOC has not changed its position and also maintains that discrimination against transgender workers violates Title VII. That puts the Republican-led commission at odds with the Trump administration’s Department of Justice, which in 2017, under then-Attorney General Jeff Sessions, announced that Title VII does not protect LGBT workers.

What to expect at the Supreme Court: Lawyers for the Zarda family and Bostock argue that Title VII’s plain language covers sexual orientation.

Congress and the Supreme Court, Bostock’s counsel argues, have clearly determined that the prohibition on discrimination “because of sex” in Title VII must be interpreted broadly, and “discrimination against an employee on the basis of sexual orientation – whether gay or straight – is fundamentally a form of discrimination based on sex.”

Their opponents, including the Trump administration, counter that the original public meaning of Title VII does not cover sexual orientation.

“That law forbids employers from treating employees of one sex better—or worse—than the other sex and doing so because of their sex,” argues Altitude Express, Zarda’s former employer. “It does not reach—and certainly no one in 1964 would have thought it reached—employment actions based on sexual orientation, because those actions do not disadvantage employees of a particular sex.”

The Justice Department agrees, adding: “The ordinary meaning of ‘sex’ is biologically male or female; it does not include sexual orientation. Congress has recognized in other antidiscrimination statutes that sexual orientation is different from sex.” Bills to add sexual orientation to Title VII, writes the U.S. solicitor general, have been introduced in every Congress since 1975 and Congress has not enacted them.

Gender identity and Title VII

The other case that the justices will hear Oct. 8 involves a Michigan funeral home and its owner, who fired Aimee Stephens after she informed the owner that she had been born as the wrong gender, that she intended to transition from male to female, and would begin living openly as a woman. Stephens had been a funeral director for six years.

After Stephens filed a discrimination complaint with the EEOC, the agency sued R.G. and G.R. Harris Funeral Homes. The ACLU joined the case for Stephens.

Why they went to the Supreme Court: A federal appellate court ruled in favor of the EEOC and Stephens for two reasons: Harris Homes violated Title VII by firing Stephens because she did not conform to the owner’s sex stereotypes about how men and women should appear and behave. Also, because Stephens is transgender, discharging her because of her gender identity is inherently a form of sex discrimination that violates Title VII.

The appellate court ruled that, “It is analytically impossible to fire an employee based on that employee’s status as a transgender person without being motivated, at least in part, by the employee’s sex.” The funeral home owner appealed to the Supreme Court.

What to expect at the Supreme Court: Lawyers for Harris Funeral Homes and the Trump Justice Department argue that in 1964 and today, sex discrimination meant employers favoring men over women, or vice versa, because of their sex.

“Treating all transgender persons less favorably than non-transgender persons does not violate that rule,” U.S. Solicitor General Noel Francisco said in the Justice Department’s brief.

The Justice Department’s lack of support from the EEOC could trigger some questions from justices when the case is argued.

The lawyer for the funeral homes’ owner wrote that if the gender was reversed, and it was “a female employee who insisted on dressing as a man while working with grieving families,” the employer, Harris Funeral Homes, would have responded the same way it responded to Stephens, therefore not disfavoring one sex over the other. “Similarly, it is not illegal ‘stereotyping’ for an employer to apply a sex-specific dress code based on biological sex,” the lawyer wrote.

The Justice Department represents the EEOC in the Supreme Court, and the EEOC’s general counsel usually signs the department’s briefs. But no EEOC lawyer signed the government’s brief in this case, despite reported pressure from the Justice Department to show a united front. The commission maintained its position on Title VII even though it has a Republican majority of two Republican-appointed members — including its new chair recently appointed by President Donald Trump — as well as one Democratic-appointed member. The Justice Department’s lack of support from the EEOC could trigger some questions from justices when the case is argued.

Stephens, represented by the American Civil Liberties Union, counters that the Supreme Court has made clear that a firing is “because of sex” where “the evidence shows treatment of a person in a manner which but for that person’s sex would be different.”

Because Harris Homes would have treated Stephens differently had her assigned sex at birth been different, adds Stephens, its decision to fire her violated Title VII. And she also was fired for failing to conform to her employer’s views of how men and women should identify, look and act, constituting illegal sex stereotyping.

Stephens’ counsel argues that the Supreme Court has said sex must be “irrelevant” in employment decisions under Title VII. “When Harris Homes fired Aimee Stephens,” her lawyer wrote in his brief, “it violated that basic premise by evaluating her based on sex and not her unquestioned ability to do her job.”